108 MODERN FRUIT MARKETING 



salinometer, 2 and which will not freeze at zero. If a 

 temperature below zero is required, chloride of calcium 

 brine is used, a mixture of three pounds per gallon 

 will not freeze at 8 degrees below zero. 



11 In the brine system the large body of chilled brine 

 contained in the brine tank and pipe coils is a storage 

 for cold, and is a reserve that can be used to maintain 

 the temperature desired in the rooms for a considerable 

 length of time, by merely operating the brine circulat- 

 ing pump. It frequently being only necessary to oper- 

 ate the compressor during the day to maintain the tem- 

 perature during the entire 24 hours. The ease with 

 which the temperature is controlled, and the absence of 

 any danger from escaping ammonia in the rooms are the 

 principal features that commend this system. 



Direct Expansion System. ' ' In the direct expansion 

 system the ammonia expansion coils are placed directly 

 in the rooms to be cooled, the heat being absorbed by 

 the evaporation of the ammonia in its passage through 

 the pipe coils to the compressor, only one system of 

 pipes being required. The expense of the outfit being 

 very materially reduced, as compared with the brine 

 system, the brine tank, the brine pump and the secondary 

 system of pipes for brine circulation being dispensed 

 with and a somewhat greater efficiency is obtained. 



"The arrangement of the pipe coils in the cold stor- 

 age rooms is the same for direct expansion as for brine 

 circulation, but the valves and fittings must all be of 

 special construction, and the pipes are put up with the 

 greatest care so as to be absolutely tight to avoid the 



2 A salinometer is a hydrometer graduated to show the percentage of 

 gait in a solution. 



